tony if you specify an et 28 , you will still have the same inner clearance on all rim sizes iirc ,

as thats the size from the hub centre line to the back of the rim , im sure martin will correct me if im wrong !!

so in answer to your Q, the extra inch will be on the outside , i run ET 0's on the back of mine for tarmac, but only on 15's, but am lookin for some 17's in the same offset !!! 8 x 17 ET 0 's - sorry martin cant afford new


i will say these new rims are the best compomotive have done for a long while

but alas , everyone will have them before long and ruin the individual look

they do look very 'speedline corse' very